If the amount of red is increased in orange, toward which colour will it shift?

Correct answer: Toward red

The governing concept is proportional colour mixing. Orange is made from red and yellow. If the red component is increased while the other component remains present, the hue becomes more reddish and shifts toward red, often described as red-orange. Thus option B is correct. Increasing yellow would move it toward yellow, while green or blue are not the expected direction of this mixture.